Fixing structure between links and pins in crawler

ABSTRACT

A pressure receiving surface ( 8 ) having a diameter gradually decreasing in an axially inward direction is formed at an outer end portion of a pin ( 1 ), whereas a pressing portion ( 7 ) is formed at a circumferential edge of an opening of a pin insertion hole ( 5 ) of a link ( 2 ). A retaining ring ( 3 ) is formed with a friction surface ( 9 ) to be press-contacted to the pressure receiving surface ( 8 ) when a force is applied from the pressing portion ( 7 ) upon development of a relative movement in a disengaging direction. The retaining ring ( 3 ) and the pressure receiving surface ( 8 ) share a greater area of contact than in the prior art, providing sufficient friction. This makes possible to provide a fastening structure of the link and the pin of a crawler belt which can be assembled by simple operation at a low cost, without requiring a high machining accuracy, and thus can be manufactured at a low cost.

TECHNICAL FIELD

[0001] The present invention relates to a fastening structure between alink and a pin of a crawler belt in a vehicle such as a constructionmachine.

BACKGROUND ART

[0002] A crawler belt utilized in a construction machine, such as abulldozer and a hydraulic shoveling machine, comprises an endlessannular link chain provided with shoes (crawler shoes) for contact withground. The link chain has such a structure that a plurality of linksare interconnected by pins. A structure of the link interconnection isshown in FIG. 8. As shown in this figure, the link chain includes apredetermined number of link pairs of a left-hand and a right-hand links31, 32 disposed in a longitudinal direction. In each of the link pairs31, 32, a pin 33 and a bushing 34 fasten an end portion of alongitudinally preceding link pair to a front portion of the followinglink pair. More specifically, the pin 33 is inserted into the bushing34, and the bushing 34 is press-fitted into rear holes 41 a, 42 a of thepreceding links 31 a, 32 a, whereas the pin 33 is press-fitted intofront holes 41 b, 42 b of the following links 31 b, 32 b. Since thebushing 34 and the pin 33 are pivotable, the preceding and the followinglinks 31 a, 31 b are connected with each other in a bendable manner likea joint. It should be noted here that, in FIG. 8, a portion indicated bynumeral 35 is a lubricating oil supplying hole. Lubricating oil suppliedhere provides lubrication between the pin 33 and the bushing 34.

[0003] According to the crawler belt described as above, the pin 33 issubjected to a large force in a direction of thrust during use.Therefore, according to the link chain described as above, a retainingmechanism for preventing the pin 33 from coming out of the links 31, 32is provided (for example, U.S. Pat. No. 4,618,190). According to thisfastening structure between link and pin, an annular recess is formedaround an opening of the pin insertion hole in the link. Further, closeto an end portion of the pin, a circumferential groove smoothlyrecessing in an axially inward direction is formed. The recess in thelink and the groove in the pin form a cavity having an annular opening,between the circumferential edge of the opening of the pin insertionhole and the outer end portion of the pin. Into this cavity, there isdriven an annular retainer made of a metal for preventing the pin fromcoming out. The retainer is plastically deformed to conform to the shapeof the cavity, so as to fill the cavity with the retainer, therebypreventing the pin from relative, disengaging movement out of the linktoward the side away from the opening.

[0004] Now, with the above described fastening structure between linkand pin, in order to prevent development of an excessive play betweenthe link and the pin, the plastic deformation of the retainer must becarried out sufficiently so that the retainer is tightly fitted toconform to the shape of the annular cavity. However, in order to achievethis, there is a need for complex machining operation, and a highdimensional accuracy in the product. In addition, the recess of the linkand the groove of the pin must be aligned with each other accurately,which leads a problem of increased cost of facility and equipment aswell as cost of manufacture.

[0005] In an attempt to solve the above described problem, the JapanesePatent Application No. Hei 11-182264, for example, proposes a fasteningstructure of link and pin, in which a retaining ring 36 is employed.Specifically, as shown in FIG. 9, an annular space 45 is formed betweena circumferential edge of an opening of pin insertion holes 41 b, 42 bof the links 31, 32 and a corresponding end portion of a pin 33. Theretaining ring 36 is disposed in this space 45, thereby preventing therelative, disengaging movement of the pin 33 toward the side away fromthe opening. In this case, there is formed a tapered inner surface 43having a diameter gradually increasing from the pin insertion hole 41 btoward outside, surrounding the opening of the pin insertion hole 41 b.On the other hand, the pin 33 is formed with a tapered outer surface 44facing the tapered inner surface 43. A slanting angle of the taperedouter surface 44, with respect to the axis, is slightly smaller than aslanting angle of the tapered inner surface 7. With this arrangement,the tapered surfaces 43, 44 are farther away from each other in theoutward direction. The retaining ring 36 is made of an annular elasticmetal having a circular section, with a part of the ring cut out so thatthe ring can elastically spread and shrink in diameter.

[0006] However, the above described fastening structure between link andpin of a crawler belt has the following problems resulting from that theopening portion of the pin insertion hole 41 b of the link 31 and theouter end portion of the pin 33 are tapered surfaces 43, 44respectively, and that the retaining ring 36 has a circular section.Specifically, first, assembling operation is costly. More specifically,since the section of the retaining ring 36 is circular, the ringcircumferential surface cannot have a sufficient area of contact witheach of the tapered surfaces 43, 44, being unable to obtain sufficientinitial friction from the elastic restoring force of the retaining ring36 alone. For this reason, in an assembling step, an operation ofdriving the retaining ring 36 inwardly is necessary. For this particularoperation of driving the retaining ring 36, a special jig dedicated tothe pressing operation must be prepared. Further, a pressing apparatuscapable of providing a necessary level of driving force is necessary. Asa result of these, a high cost is required for the assembling operation.

[0007] Secondly, in order to achieve a desired friction as after theassembling, the tapered inner surface 43 and the tapered outer surface44 have to be machined to a high accuracy. Specifically, if the anglemade by the two tapered surfaces 43, 44 is too large, the retaining ring36 cannot be held by the friction and moves away, becoming unable toprovide the expected function. For example, in the state shown in FIG.9, it has been confirmed that the angle θ between the tapered surfaces43, 44 must be smaller than 20° approximately. As a result of such ahigh machining accuracy required of each part, manufacturing cost ofthese has to increase.

[0008] The present invention is made to solve the above describedproblems, with an object to provide a fastening structure between linkand pin of a crawler belt which can be assembled by simple operation ata low cost, without requiring a high machining accuracy, and thus can bemanufactured at a low cost.

DISCLOSURE OF THE INVENTION

[0009] Now, a fastening structure of link and pin of a crawler beltaccording to a first invention is a fastening structure of a link and apin in a crawler belt of a vehicle. An annular space 15 is formedbetween a circumferential edge of an opening of a pin insertion hole 5of a link 2 and an outer end portion of a pin 1 to be inserted in thepin insertion hole 5, and a retaining ring 3 is disposed in the space 15whereby preventing relative, disengaging movement of the pin 1 toward aside away from the opening. The structure is characterized in that oneof the circumferential edge of the opening of the pin insertion hole 5of the link 2 and the outer end portion of the pin 1 is formed with atapered pressure receiving surface 8 having a diameter graduallydecreasing in an axially inward direction, the other is formed with apressing portion 7, and the retaining ring 3 is formed with a frictionsurface 9 to be press-contacted to the pressure receiving surface 8 by aforce from the pressing portion 7 upon development of the relativemovement in the disengaging direction. It should be noted here that thepressing portion 7 may be an edge portion as in the first embodimentthrough the third embodiment, or may be a tapered pressure receivingsurface as in the fourth embodiment. In this case, a portion of theretaining ring 3 contacted by the pressing portion 7, (a pressedsurface), is formed as a friction surface as in the fourth embodiment.

[0010] According to the fastening structure between link and pin of acrawler belt provided by the first invention, the following function isperformed. First, if the pin 1 makes a relative movement in thedisengaging direction toward the side away from the opening, then thepressing portion 7 of the link 2 contacts the pressed surface 10 of theretaining ring 3, and the friction surface 9 of the retaining ring 3press-contacts the tapered, pressure receiving surface 8. Under thisstate, the ring 3 is under a force acting in the disengaging direction.This force F₁ can be divided into a component force F₂ acting verticallyto the pressure receiving surface 8 and another component force F₃acting along the pressure receiving surface 8. Based on this, therelative, disengaging movement toward the side away from the opening isprevented by selecting a condition that makes friction generated by thecomponent force F₂ acting vertically to the pressure receiving surface 8greater than the component force F₃ acting along the pressure receivingsurface 8. Specifically, the pressure receiving surface 8 slantedaxially inward is given a slant angle α that satisfies the abovementioned relationship μ·F₂>F₃ (where μ represents frictioncoefficient), thereby preventing the pin from relative, disengagingmovement out of the link toward the side away from the opening.

[0011] According to the fastening structure of link and pin of a crawlerbelt provided by the first invention, the retaining ring 3 contacts thepressure receiving surface 8 via its friction surface 9. For thisreason, the retaining ring 3 has a greater area of contact with thepressure receiving surface 8 than in the prior art. Therefore, elasticrestoring force of the retaining ring 3 alone can generate sufficientinitial friction. Thus, there no longer is the need for the operation ofinwardly driving the retaining ring 3 during the assembly. As a result,there no longer is the need for the special jig and the pressingapparatus for driving the ring 3, and as a result, it becomes possibleto reduce cost necessary for the assembling operation.

[0012] Further, the slant angle α of the pressure receiving surface 8slanting axially inward should only satisfy the above mentionedrelationship μ·F₂>F₃. Thus, there no longer is the need for highmachining accuracy in the angle of the tapered surface as is in theprior art, and therefore it becomes possible to reduce relevantmanufacturing cost.

[0013] A fastening structure between link and pin of a crawler beltaccording to a second invention is characterized in that the retainingring 3 includes a pressed surface 10 contacted by the pressing portion7, and the friction surface 9, whereas the pressed surface 10 and thefriction surface 9 are farther away from each other in an outwarddirection.

[0014] According to the fastening structure between link and pin of acrawler belt provided by the second invention, the friction surface 9and the pressed surface 10 of the retaining ring 3 are farther away fromeach other in the outward direction. Therefore, even if there isinconsistency in an engaging dimension between the pressing portion 7and the pressure receiving surface 8 resulting from machining error,assembling error and so on, the friction surface 9 and the pressedsurface 10 of the retaining ring 3 can make respective engagements atvarious dimensions, which means an engageable range for the two isincreased. As a result, it becomes possible to allow for more generoustolerance in the shape and dimensions of the pressing portion 7 in thelink 2 and of the pressure receiving surface 8 in the pin 1 than in theprior art.

[0015] A fastening structure between link and pin of a crawler beltaccording to a third invention is characterized in that the retainingring 3 has a square section.

[0016] According to the fastening structure between link and pin of acrawler belt provided by the third invention, since the retaining ring 3has a square section, manufacture thereof becomes easy, and can beembodied at a low cost.

[0017] A fastening structure between link and pin of a crawler beltaccording to a fourth invention is characterized in that the pressingportion 7 is formed like an edge.

[0018] According to the fastening structure between link and pin of acrawler belt provided by the fourth invention, by making one of thecircumferential edge of the opening of the pin insertion hole 5 of thelink 2 and the outer end portion of the pin 1 as the edge-like pressingportion 7, it becomes possible to allow for even more generous tolerancein the shape and dimensions of the pressing portion 7 in the link 2 andof the pressure receiving surface 8 in the pin 1 than in the case whereboth are made as tapered pressure receiving surfaces.

[0019] A fastening structure between link and pin of a crawler beltaccording to a fifth invention is a fastening structure of a link and apin in a crawler belt of a vehicle. An annular space is formed between acircumferential edge of an opening of a pin insertion hole 5 of a link 2and an outer end portion of a pin 1 inserted in the pin insertion hole5, and a retaining ring 3 is disposed in the space 15 whereby preventingrelative disengaging movement of the pin 1 toward a side away from theopening. The structure is characterized in that one of thecircumferential edge of the opening of the pin insertion hole 5 of thelink 2 and the end portion of the pin 1 is formed with a taperedpressure receiving surface 8 having a diameter gradually decreasing inan axially inward direction, the other is formed with an edge-likepressing portion 7, and the retaining ring 3 press-contacts each of thepressing portion 7 and the pressure receiving surface 8.

[0020] According to the fastening structure between link and pin of acrawler belt provided by the fifth invention, the following function isperformed. First, in an assembling step, when the retaining ring 3 isdisposed in the space 15 and the retaining ring 3 is pushed inward, thenthe edge-like pressing portion 7 is press-contacted to the retainingring 3 whereas the retaining ring 3 is press-contacted to the taperedpressure receiving surface 8. Under this state, a vicinity of thecontacting portion in the retaining ring 3 is elastically deformed bythe pressure, providing a surface on the retaining ring 3 on the sidefacing the pressure receiving surface 8. In other words, a frictionsurface 9 contacting the pressure receiving surface 8 is created.Therefore, if the pin 1 tends to make relative movement in thedisengaging direction toward the side away from the opening under thisstate, then the retaining ring 3 comes under a force F₁ acting in thedisengaging direction. This force F₁ can be divided into a componentforce F₂ acting vertically to the pressure receiving surface 8 andanother component force F₃ acting along the pressure receiving surface8. Based on this, the relative, disengaging movement of the pin towardthe side away from the opening is prevented by selecting a conditionthat makes friction generated by the component force F₂ actingvertically to the pressure receiving surface 8 greater than thecomponent force F₃ acting along the pressure receiving surface 8.Specifically, the pressure receiving surface 8 slanted axially inward isgiven a slant angle α that satisfies the above mentioned relationshipμ·F₂>F₃ (where μ represents friction coefficient), thereby preventingthe pin from relative, disengaging movement out of the link toward theside away from the opening.

[0021] According to the above described fastening structure between linkand pin of a crawler belt provided by the fifth invention, the retainingring 3 has the friction surface 9 provided by the assemblage, makingcontact with the pressure receiving surface 8. Therefore, the retainingring 3 has a greater area of contact with the pressure receiving surface8 than in the prior art, making possible to obtain sufficient initialfriction. Further, since one of the circumferential edge of the openingof the pin insertion hole 5 of the link 2 and the outer end portion ofthe pin 1 is made into the edge-like pressing portion 7, the retainingring 3 receives the pressure at a point, and thus it becomes possible toperform the assembling operation more easily, using less pressing forcethan in the case where the two members are each formed with a taperedsurface, i.e. than in the case where the pressure is received on asurface. As a result, operating efficiency in the assembling operationcan be improved.

[0022] Further, the slant angle α of the pressure receiving surface 8slanting axially inward should only satisfy the above mentionedrelationship μ·F₂>F₃. Thus, there no longer is the need for highmachining accuracy in the angle of the tapered surface as is in theprior art, and therefore it becomes possible to reduce relevantmanufacturing cost. Further, since one of the link 2 and the pin has theedge-like pressing portion 7, it becomes possible to allow for moregenerous tolerance in the shape and dimensions of the link 2 and of thepin 1 than in the case where both are made as tapered pressure receivingsurfaces.

[0023] A fastening structure between link and pin of a crawler beltaccording to a sixth invention is characterized in that the retainingring 3 has a circular section.

[0024] According to the fastening structure between link and pin of acrawler belt of the sixth invention, since the retaining ring 3 has acircular section, manufacture thereof becomes easy, making possible toembody at a low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is an enlarged sectional view showing a principal portionof a first embodiment of a fastening structure of link and pin of acrawler belt according to the present invention.

[0026]FIG. 2 is an enlarged sectional view of a principal portion,showing an operating state of the above embodiment.

[0027]FIG. 3 is an enlarged sectional view showing a principal portionof a second embodiment.

[0028]FIG. 4 is an enlarged sectional view showing a principal portionof a third embodiment.

[0029]FIG. 5A is an enlarged sectional view of a principal portion fordescribing a state of assembly in the third embodiment.

[0030]FIG. 5B is an enlarged sectional view of a principal portion fordescribing another state of assembly in the third embodiment.

[0031]FIG. 6 is an enlarged sectional view showing a principal portionof a fourth embodiment.

[0032]FIG. 7A is an enlarged sectional view of a principal portionshowing a state before assembly in a fifth embodiment.

[0033]FIG. 7B is an enlarged sectional view of a principal portionshowing a state after assembly in the fifth embodiment.

[0034]FIG. 8 is a sectional view showing an example of a fasteningstructure of a link and a pin of a crawler belt in a prior art crawlerbelt link chain.

[0035]FIG. 9 is an enlarged sectional view showing a principal portionof the prior art.

BEST MODE FOR CARRYING OUT THE INVENTION

[0036] Next, specific embodiments of the fastening structure of link andpin of a crawler belt according to the present invention will bedescribed in detail with reference to the accompanying figures. First,the retaining mechanism itself is exactly the same as the prior artshown in FIG. 8 and FIG. 9, comprising a pin 1, a link 2 and a retainingring 3. Therefore, the description to be given here below will primarilyfocus on characteristic points.

[0037] First, as shown in FIG. 1, the pin 1 has an end, close to which acircumferential groove 4 having a generally triangular section isformed. Further, the link 2 is formed with a pin insertion hole 5 intowhich the pin 1 is press-fitted. The pin insertion hole 5 has anopening, around which an annular recess 6 is formed. The groove 4 of thepin 1 and the recess 6 of the pin insertion hole 5 form an annularfitting space 15 recessing axially inward and having an annular opening,between a circumferential edge of the opening of the pin insertion hole5 and the outer end portion of the pin 1. The recess 6 meets an edge ofthe opening of the pin insertion hole 5. This edge serves as a pressingportion 7, function of which will be described later. The groove 4 ofthe pin 1 includes a tapered outer surface 8 facing the pressing portion7. The tapered outer surface 8 gradually shrinks in diameter axiallyinwardly, and as will be described later, serves as a pressure receivingsurface. The retaining ring 3 is made of an annular elastic metal, witha part of the ring cut out so that the ring can elastically spread andshrink in diameter. Further, the retaining ring 3 has a generally squaresection, with one corner of the square being in an inner diameter region(the lower side as in the figure) and another corner being in an outerdiameter region (the upper side as in the figure).

[0038] According to the above described fastening structure between linkand pin of a crawler belt, assembling operation can be completed bysimply press-fitting the pin 1 into the pin insertion hole 5 of the link2, then spreading and disposing the retaining ring 3 into the groove 4of the pin 1, and finally removing the spreading force thereby allowingthe retaining ring 3 to elastically shrink in diameter. Under thisstate, the retaining ring 3 has its inner diameter side contacting thetapered outer surface 8 whereas the outer diameter side has its innerside surface contacting the pressing portion 7. Hereinafter, in theretaining ring 3, the surface contacting the tapered outer surface 8(i.e. the outer side surface on the inner diameter side) will be calleda friction surface 9, and the surface contacting the pressing portion 7(i.e. the inner side surface on the outer diameter side) will be calleda pressed surface 10.

[0039] Under the state of assembly as described above, if the link 2tends to move out of the pin 1, the following function prevents thedisengaging movement. Specifically, first, if the link 2 tends to moverightward as in FIG. 1 (i.e. if the pin 1 tends to make a relativemovement in a disengaging direction toward the side away from theopening), then the pressing portion 7 of the link 2 presses the pressedsurface 10 of the retaining ring 3, twisting the retaining ring 3outward as shown in FIG. 2, thereby making the friction surface 9 of theretaining ring 3 contact the tapered outer surface, i.e. the pressurereceiving surface 8. Under this state, the ring 3 is under a forceacting in the disengaging direction (to the right as in the figure).This force F₁ can be divided into a component force F₂ acting verticallyto the pressure receiving surface 8 and another component force F₃acting along the pressure receiving 8. If the friction generated by thecomponent force F₂ acting vertically to the pressure receiving surface 8is greater than the component force F₃ acting along the pressurereceiving surface 8, then the relative, disengaging movement of the pin1 toward the side away from the opening is prevented. For this purpose,the pressure receiving surface 8 slanted axially inward is given a slantangle α that satisfies the above mentioned relationship μ·F₂>F₃ (where μrepresents friction coefficient).

[0040] According to the fastening structure of link and pin of a crawlerbelt described above, the retaining ring 3 contacts the pressurereceiving surface 8 via its friction surface 9. For this reason, theretaining ring 3 has a greater area of contact with the pressurereceiving surface 8 than in the prior art. Therefore, elastic restoringforce of the retaining ring 3 alone can generate sufficient initialfriction. Thus, there no longer is the need for the operation ofinwardly driving the retaining ring 3 during the assembly. As a result,there no longer is the need for the specialized jig and the pressingapparatus for driving the retaining ring 3, and as a result, it becomespossible to reduce cost necessary for the assembling operation. Further,the shape of the pressing portion 7 and the pressure receiving surface8, and material characteristic of the retaining ring 3 are so selectedthat even if the pin 1 and the link 2 are disassembled for a purpose ofrepair and so on, the retaining ring 3 can be reused since the retainingring 3 is only elastically deformed at the time of the assembly.

[0041] Further, the slant angle α of the pressure receiving surface 8slanting axially inward should only satisfy the above mentionedrelationship μ·F₂>F₃. Thus, there no longer is the need for highmachining accuracy in the angle of the tapered surface as is in theprior art, and therefore it becomes possible to reduce relevantmanufacturing cost. Further, the edge-like pressing portion 7 providedin the line 2 makes possible to allow for more generous tolerance in theshape and dimensions of the pressing portion 7 in the link 2 and of thepressure receiving surface 8 in the pin 1 than in the case where bothare made as tapered pressure receiving surfaces.

[0042] Further, according to the prior art fastening structure of linkand pin, the tapered surface 44 must be formed also in the link 2.However, since the link 2 has a non-circular outer shape, it is verydifficult to form a tapered annular surface 44 in such an object as thelink 2. On the contrary, according to the embodiment described above,the link 2 should only be formed with the pressing portion 7, and thereis no need for forming the tapered surface. This leads to an advantageof simplified machining operation.

[0043]FIG. 3 shows a second embodiment, in which the retaining ring 3has a square section like the embodiment shown in FIG. 1. The differencehowever, is that the shape of a vicinity of the pressing portion 7 inthe link 2 changed. Specifically, a tapered guide surface 11 having adiameter decreasing in an axially inward direction is formed on anoutward side of the pressing portion 7. At the time of assembly, theguide surface 11 allows the pressed surface 10 of the retaining ring 3to reliably contact the pressing portion 7, thereby making easy theassembling operation of the retaining ring 3. According to thisembodiment, again, the same function and effect as achieved in the firstembodiment can be obtained.

[0044]FIG. 4 shows a third embodiment, in which the retaining ring 3 hasa different shape in section. In this case, the section is not square asin the embodiments in FIG. 1 and FIG. 2 (in which the friction surface 9and the pressed surface 10 are parallel to each other). Instead, thefriction surface 9 and the pressing surface 10 are each tapered to havean outwardly increasing diameter, and further, a distance between thetwo surfaces increases in the outward direction. It should be noted herethat the retaining ring 3 is given a laterally mirror symmetric sectionin the figure, so that the ring can be used also at the other endportion of the pin 1.

[0045] Again, according to this fastening structure of link and pin of acrawler belt provided by the third embodiment, the same function andeffect as achieved in the above can be obtained. In addition, there isanother advantage in that even more generous tolerance can be allowedfor in the shape and dimensions of the pressing portion 7 in the link 2and of the pressure receiving surface 8 in the pin 1 than in the abovedescribed embodiments. Specifically, since the friction surface 9 andthe pressed surface 10 of the retaining ring 3 are disposed in anoutwardly opening taper pattern, as shown in FIG. 5A and FIG. 5B, theretaining ring 3 can now make engagement between the pressing portion 7and the pressure receiving surface 8 not only at a place closer to theopening of the space 15 (FIG. 5A) but also at a place farther from theopening (FIG. 5B), making possible to prevent relative movement of thepin 1 in the disengaging direction. In other words, even if there isinconsistency in engaging dimension between the pressing portion 7 andthe pressure receiving surface 8 resulting from machining error,assembling error and so on, the friction surface 9 and the pressedsurface 10 of the retaining ring 3 are not limited in a certain fixedengaging dimension, and therefore can make respective engagements atvarious dimensions. This means an engagable range for the two surfacesis increased.

[0046]FIG. 6 shows a fourth embodiment. In this embodiment, theretaining ring 3 has the same sectional shape as in FIG. 4 and FIG. 5,whereas the pressing portion 7 of the link 2 is made as a tapered,pressure receiving surface having a diameter gradually decreasing in anaxially inward direction. Specifically, in this case, a pin insertionhole 5 also is formed with a pressure receiving surface 7 around theopening, in addition to the pressure receiving surface 8 formed at theouter end portion of the pin 1. With this arrangement, a distancebetween the pressure receiving surfaces 7, 8 gradually increasesoutwardly. According to this embodiment, a pressed surface 10 of theretaining ring 3 serves as a friction surface, i.e. both of the frictionsurfaces 9, 10 make contact with the pressure receiving surfaces 7, 8respectively. Such a structure as the above brings about the functionsand effects described earlier, and in addition, it becomes possible tofurther reliably prevent the relative movement of the pin 1 in thedisengaging direction since the retaining ring 3 now has even moreincreased area of contact. It should be noted here that in this caseagain, the retaining ring 3 is given a laterally mirror symmetricsection as in the figure, so that the ring can be used also at theopposite end portion of the pin 1.

[0047]FIG. 7A and FIG. 7B show a fifth embodiment, in which theretaining ring 3 is made to have a circular section. Hereinafter,detailed description will be made with reference to FIG. 7A and FIG. 7B.Referring first to FIG. 7A, the pin 1 has an end, close to which acircumferential groove 4 having a generally triangular section isformed. Further, the link 2 is formed with a pin insertion hole 5 intowhich the pin 1 is press-fitted. The pin insertion hole 5 has anopening, around which an annular recess 6 is formed. The groove 4 of thepin 1 and the recess 6 of the pin insertion hole 5 form an annularfitting space 15 recessing axially inward and having an annular opening,between a circumferential edge of the opening of the pin insertion hole5 and the outer end portion of the pin 1. Further, an edge-like pressingportion 7 is formed at a location where the recess 6 meets the openingof the pin insertion hole 5, further outward of which, starting from thepressing portion 7 in an outward direction, there is formed an axiallyslanted, tapered guide surf ace 11 gradually increasing in diameter. Thegroove 4 of the pin 1 has a tapered outer surface 8 facing the pressingportion 7. The tapered outer surface 8 gradually increases in diameterin the axially outward direction, and as will be described later, servesas a pressure receiving surface. With this arrangement, the taperedouter surface (hereinafter called a pressure receiving surface 8) has aslanting angle, slanting with respect to the axis, smaller than aslanting angle of the guide surface 11. On the other hand, the retainingring 3 is made of an annular elastic metal, with a part of the ring cutout so that the ring can elastically spread and shrink in diameter.Further, the retaining ring 3 has a generally circular section, beingpress-contacted to the pressing portion 7 and the pressure receivingsurface 8 in the above mentioned space 15.

[0048] With the above-described fastening structure between link and pinof a crawler belt, assembling operation involves press-fitting the pin 1into the pin insertion hole 5 of the link 2, then spreading anddisposing the retaining ring 3 into the groove 4 of the pin 1, and thenremoving the spreading force thereby allowing the retaining ring 3 toelastically shrink in diameter. Thereafter, the retaining ring 3 ispushed inwardly into the space 15 to complete the assembly. Under thisstate shown in FIG. 7B, the retaining ring 3 has its outer diameter sidepress-contacted by the edge-like pressing portion 7 whereas the innerdiameter portion press-contacted by the tapered pressure receivingsurface 8. Under this state, a vicinity of the press-contacted portionin the retaining ring 3 is elastically deformed by the pressure,providing a surface on the retaining ring 3, on the side facing thepressure receiving surface 8. In other words, a friction surface 9contacting the pressure receiving surface 8 is created.

[0049] Under the state of assembly as described above, if the link 2tends to move out of the pin 1, the following function controls thedisengaging movement. Specifically, under the sate where the pressingportion 7 of the link 2 press-contacts the retaining ring 3 and thefriction surface 9 of the retaining ring 3 press-contacts the pressurereceiving surface 8 of the pin 1, if the link 2 tends to move rightwardas in FIG. 7 (i.e. if the pin 1 tends to make a relative movement in thedisengaging direction toward the side away from the opening), then theretaining ring 3 comes under a force acting toward the disengagingdirection (to the right as in the figure). This force F₁ can be dividedinto a component force F₂ acting vertically to the pressure receivingsurface 8 and another component force F₃ acting along the pressurereceiving 8. If the friction generated by the component force F₂ actingvertically to the pressure receiving surface 8 is greater than thecomponent force F₃ acting along the pressure receiving surface 8, thenthe relative disengaging movement of the pin toward the side away fromthe opening is prevented. Therefore, according to this embodiment, thepressure receiving surface 8 slanted axially inward is given a slantangle α that satisfies the above mentioned relationship μ·F₂>F₃ (where μrepresents friction coefficient).

[0050] According to the above described fastening structure between linkand pin of a crawler belt, the friction surface 9 of the retaining ring3 provided by the assemblage makes contact with the pressure receivingsurface 8. Therefore, the retaining ring 3 has a greater area of contactwith the pressure receiving surface 8 than in the prior art, makingpossible to obtain sufficient initial friction. Further, since theretaining ring 3 receives the pressure at a point, it becomes possibleto perform the assembling operation more easily, using less pressingforce than in the case where the two members are each formed with atapered surface, i.e. than in the case where the pressure is received ona surface. As a result, operating efficiency in the assembling operationcan be improved. Further, the shape of the pressing portion 7 and thepressure receiving surface 8 and material characteristic of theretaining ring 3 are so selected that even if the pin 1 and the link 2are disassembled for a purpose of repair and so on, the retaining ring 3can be reused since the retaining ring 3 is only elastically deformed atthe time of the assembly.

[0051] Further, the slant angle α of the pressure receiving surface 8slanting axially inward should only satisfy the above mentionedrelationship μ·F₂>F₃. Thus, there no longer is the need for highmachining accuracy in the angle of the tapered surface as is in theprior art, and therefore it becomes possible to reduce relevantmanufacturing cost. Further, the edge-like pressing portion 7 in thelink 2 according to the present embodiment makes possible to allow formore generous tolerance in the shape and dimensions of the pressingportion 7 in the link 2 and of the pressure receiving surface 7 in thepin 1 than in the case where both are made as tapered pressure receivingsurfaces.

[0052] Further, according to the prior art fastening structure of linkand pin, the tapered surface 44 must be formed also in the link 2.However, since the link 2 has a non-circular outer shape, it is verydifficult to form a tapered annular surface 44 in such an object as thelink 2. On the contrary, according to the embodiment described above,the link 2 should only be formed with the edge-like pressing portion 7,and there is no need for forming the tapered surface. This leads to anadvantage of simplified machining operation.

[0053] Embodiments of the fastening structure between link and pin of acrawler belt according to the present invention being described thusfar, the fastening structure between link and pin of a crawler beltaccording to the present invention is not limited to those described inthe embodiments, but can be varied in many ways. For example, accordingto the embodiments, the pressure receiving surface 9 is formed in thepin 1 and the pressing portion 7 is formed in the link 2. Conversely,however, the pressing portion 7 may be formed in the pin 1 and thepressure receiving surface 9 may be formed in the link 2. Further, thesectional shape of the retaining ring 2 is preferably mirror symmetricas in the above embodiments, for usability at either end of the pin 1.However, the shape may not be mirror symmetric depending on a situation,though the square or circular section as in FIG. 1, FIG. 3 or FIG. 7brings about such advantages as easiness in manufacture and low cost inapplication.

1. A fastening structure of link and pin of a vehicle crawler belt,wherein an annular space (15) being formed between a circumferentialedge of an opening of a pin insertion hole (5) of a link (2) and anouter end portion of a pin (1) to be inserted in the pin insertion hole(5), a retaining ring (3) being disposed in the space (15) wherebypreventing relative, disengaging movement of the pin (1) toward a sideaway from the opening; characterized in that one of the circumferentialedge of the opening of the pin insertion hole (5) of the link (2) andthe outer end portion of the pin (1) is formed with a tapered pressurereceiving surface (8) having a diameter gradually decreasing in anaxially inward direction, the other being formed with a pressing portion(7), and the retaining ring (3) being formed with a friction surface (9)to be press-contacted to the pressure receiving surface (8) by a forcefrom the pressing portion (7) upon development of the relative movementin the disengaging direction.
 2. The fastening structure of link and pinof a vehicle crawler belt according to claim 1, characterized in thatthe retaining ring (3) includes a pressed surface (10) contacted by thepressing portion (7), and the friction surface (9); the pressed surface(10) and the friction surface (9) being farther away from each other inan outward direction.
 3. The fastening structure of link and pin of avehicle crawler belt according to claim 1 or claim 2, characterized inthat the retaining ring (3) has a square section.
 4. The fasteningstructure of link and pin of a vehicle crawler belt according to one ofclaim 1˜claim 3, characterized in that the pressing portion (7) isformed like an edge.
 5. A fastening structure of link and pin of avehicle crawler belt, wherein an annular space (15) being formed betweena circumferential edge of an opening of a pin insertion hole (5) of alink (2) and an outer end portion of a pin (1) to be inserted in the pininsertion hole (5); a retaining ring (3) being disposed in the space(15) whereby preventing relative disengaging movement of the pin (1)toward a side away from the opening; characterized in that one of thecircumferential edge of the opening of the pin insertion hole (5) of thelink (2) and the end portion of the pin (1) is formed with a pressurereceiving surface (8) having a diameter gradually decreasing in anaxially inward direction, the other being formed with an edge-likepressing portion (7), and the retaining ring (3) press-contacting eachof the pressing portion (7) and to the pressure receiving surface (8).6. The fastening structure of link and pin of a vehicle crawler beltaccording to claim 5, characterized in that the retaining ring (3) has acircular section.